Recently, indoor visible light localization has become attractive. Unfortunately, its performance is limited by diffuse reflection. The diffuse reflection is estimated by the bilinear interpolation-based method. A received signal strength-based iterative visible light positioning algorithm is proposed to reduce the influence of diffuse reflection by subtracting the estimated diffuse reflection signal from the received signal. Simulations are made to evaluate the proposed iterative positioning algorithm in a typical scenario with different parameters of the field-of-view (FOV) of the receiver and the reflectivity of the wall. Results show that the proposed algorithm can reduce the average positioning error by 12 times in a typical scenario and can reduce the positioning error greatly with various FOV of the receiver and the reflectivity of the wall. The proposed algorithm is effective and robust to reduce the degradation caused by diffuse reflection in a positioning system and will have many potential applications in indoor localization scenarios.
For indoor visible light communication (VLC) systems aim to achieve communication and illumination simultaneously, the channel capacity are significantly affected by illumination demands in actual scenarios. To enhance the system performance, the wavelength division multiplex (WDM) technique can be introduced. In this letter, we analyzed the demands of illuminance and chromaticity’s influence on indoor WDM visible light communication system based on color light emitting diodes (LED). The spectra distribution, crosstalk and noise of WDM VLC system were analyzed and the relative optimal total channel capacity was obtained by optimizing the number of sub-channels and their intensity at standard illumination scenario. It’s shown that by applying WDM technique, the total channel capacity of LED based VLC system can be about 4 times than the situation of single sub-channel, even with indoor illumination constraints. What’s more, the system performance can be improved by adjusting appropriate number of sub-channels and their intensity accordingly.
KEYWORDS: Ultraviolet radiation, Detection and tracking algorithms, Antennas, Telecommunications, Computer simulations, Signal to noise ratio, Monte Carlo methods, Atmospheric turbulence, Scattering, Non-line-of-sight propagation
Affected by atmospheric turbulence and multipath transmission, inter-symbol interference (ISI) is generated, and
communication speed is limited in the channel of non-line-of-sight ultraviolet (NLOS UV) communication. Thus, MIMO
space division multiplexing (MIMO-SDM) technology has a significant effect to reduce co-channel interference, fading
and improve the transmission rate. Combined with characteristics of UV channel and noise, model of UV
communication MIMO channel and channel capacity is developed, and the application of SDM technology based on
vertical bell laboratories layered space-time coding (V-BLAST) is investigated. Also bit error rate (BER) performances
with zero-forcing (ZF), minimum mean square error (MMSE) detection algorithm are obtained. Simulation results show
that the capacity of UV communication MIMO channel is related to the number of transmit and received antennas , and
channel SNR. And the BER performance with MMSE detection algorithm is better than ZF detection algorithm.
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